1. Field of the Invention
The present invention relates to a network relay apparatus used for relay in a network.
2. Description of the Related Art
With a view to assuring the redundancy of a layer 2 network, network relay apparatuses for relaying frames are connected to form a ring network. A redundant protocol used in such a ring network configuration of the network relay apparatuses is called a ring protocol. In the occurrence of some failure on a route in the network, the network relay apparatus receiving a frame performs a flooding operation to relay the received frame in the ring protocol.
The conventional network relay apparatus performs flooding with setting all the ports other than the frame-receiving port as the flooding target. Frames sent by the flooding operation may apply the heavy load on the frequency band of the communication line. Frames are sent to even devices that do not require the frames by the flooding operation. This is undesirable from the security viewpoint.
These phenomena are not characteristic of the ring protocol but are observed in other protocols used in different network configurations.